Production of fibres of acrylonitrile polymers



United States Patent 3,122,412 PnooUcrioN or arenas or ACRYLONITRILE rotrsnins Jacques Andre Armand Menault, Venissieux, France, assignor to Crylor, haris, France, a French body corporate No Drawing. Filed July 27, 1960, Ser. No. 45,558

Claims priority, application France .luiy 30, 1959 1!) Claims. (Cl. 8-4301) This invention concerns a new process for the treatment of undrawn filaments of acrylonitrile polymers to irnprove their drawing properties.

By acrylonitrile polymers are meant acrylonitrile homopolymer as well as copolymers and grafted polymers containing from 85% to 100% of acrylonitrile and up to 15 of one or more copolymerisable ethylenic compounds, and mixtures of such polymers.

By undrawn filaments are meant filaments made by dry or wet spinning before they have undergone their complete drawing. They may have undergone a treatment for the extraction of the solvent employed in their spinning, for example by washing, and/or a preliminary drawing. Depending upon the subsequent use for which they are intended, these filaments are combined in groups to form either yarns of relatively low count, which will be employed as continuous yarns, or tows of higher count which will thereafter be cut or cracked to obtain staple fibre. it is these filaments combined in groups of variable size which are treated in accordance with the invention and then drawn.

It has now been found that it is possible to considerably improve the drawing properties of undrawn filaments of acrylonitrile polymers by subjecting them at least once, between their extrusion and their drawing, to the action of an aliphatic ketone.

Examples of ketones which can be used in accordance with the invention include acetone, methyl ethyl ketone, d-iethyl ketone, etc.

The treatment or treatments of the invention can be carried out at any desired instant between the extrusion of the filaments and their final drawing. For example, the filaments may be passed through a bath containing a ketone immediately after they leave the spinning zone, or the spinning solvent can be extracted by one or more washings with a ketone, or one or more immersions in a ketone may be effected before or after elimination of the solvent by known means, or a number of these treaments may be carried out in conjunction. The treatment or treatments according to the invention may be effected either continuously or discontinuously, if desired after a preliminary drawing.

The duration of the treatment or treatments of the invention may vary within wide limits. In any case, it must be suiiicient to ensure good contact of the filaments with the ketone. For example, in the case of the discontinuous immersion of a larger or compact wound package of filaments, the duration of the immersion must be sufficient to ensure contact of the ketone with all the filaments as far as the centre of the package. An immersion duration of from to 30 minutes is then generally preferred. If the filaments are continuously passed through the bath containing the ketone, a virtually instantaneous contact may be sufiicient in the case of a gr up of filaments of relatively low count.

When the filaments must undergo a number of treatments, including one with a ketone, between their extrusion and their final drawing, it is generally advantageous, in order to obtain maximum effectiveness, to carry out the treatment with the ketone as close as possible to the final drawing, although the improvement in the drawing properties which is due to the treatment with 3,122,412 Patented Feb. 25, 1964 the ketone is appreciable even after a number of intermediate washings with water.

It is generally advantageous to add to the last ketone bath before the final drawing a small quantity of an oiling agent soluble in the ketone, such as a condensation product of ethylene oxide with a fatty alcohol, an alkyl higher fatty acid ester such as butyl stearate, etc.

After the treatment or treatments of the invention, the final drawing may be carried out by known means.

One of the main advantages of the present invention resides in the fact that owing to the greatly improved drawing properties of the treated yarns it is possible to increase the extent of the drawing, and therefore the tenacity of the drawn yarn, while maintaining its flexibility and elongation.

Thus, the maximum degree of drawing, i.e. the degree of drawing above which breakage of the yarn occurs, is considerably higher than in the case of an untreated yarn. Moreover, the laws governing the tension during drawing are fundamentally modified. Thus, with a yarn treated in accordance with the present invention the tension necessary for the drawing is substantially independent of the extent of the drawing, while in the case of the untreated yarn the tension necessary increases with the extent of drawing.

These results are particularly surprising.

Moreover, an undrawn yarn treated entirely with a ketone, such for example as acetone, from the time of its extrusion, and thus in a completely dry state, possesses before drawing a high elongation at ambient temerature, as also great flexibility, while an untreated yarn has very low elongation and has no flexibility, so that it is rendered brittle in the course of the manipulations. Another advantage of the process is that it makes it possible to draw a treated yarn to the same extent as an untreated yarn but with greater safety, i.e. without the risk or" the formation of hairs on the yarn as a result of the rupture of a number of filaments during the drawing.

The following examples illustrate the invention:

Example I A polyacrylonitrile yarn obtained by dry spinning a solution of polyacrylonitrile in dimethylfcrmamide is washed with water in order to remove the residual solvent and then immersed at room temperature for 10 minutes in a bath of diethylketone containing 1% of a condensation product of ethylene oxide with a fatty alcohol, calculated on the weignt of yarn immersed. It is thereafter drawn in steam at a temperature of 98 C.

This yarn can be readily drawn to twelve times its origi nal length, wln'le a comparison specimen not washed with diethylketone cannot easily be drawn beyond 6.5 times its original length. The final tenacity of the yarn treated with diethylketone is considerably greater than that of the comparison specimen, though its elongation is substantially the same.

Example 11 Example III A copolymer yarn containing by wei ht of acrylontirlle and 10% by weight of vinyl dimethylaminoethyl eti er obtained by dry spinning is treated just bei is first twice washed with water.

fore it leaves the spinning cell according to French Patent 1,052,539, except that the aqueous liquid is replaced by acetone at room temperature. The yarn is thereafter washed with water to remove the residual solvent. The yarn thus obtained is readily drawn by a factor of 9, while a yarn obtained under the same con-- ditions, but using the aqueous liquid of the aforesaid patent instead of acetone, can only with difficulty be drawn to more than 6 times its original length.

Example IV A yarn obtained by dry spinning a mixture of 85% by weight of polyacrylonitrile and 15% by weight of polyvinyl acetate is treated just before it leaves the spinning cell with an aqueous liquid in accordance wtih the aforesaid French Patent 1,052,539. The yarn obtained has a Water content of 100% of its dry weight. It is successively treated in three acetone baths at room temperature. The water content of the yarn varies as follows:

After the first bath: 30% of water After the second'bath: 12% of water After the third bath: 4% of water The third bath contains 1% of a condensation prodnot of ethylene oxide with a fatty alcohol, calculated on the weight of the treated yarn.

The yarn thus obatined can readily be drawn to 12 times its original length, while a yarn treated in the same way, but with Water instead of acetone, can only with difficulty be drawn to more than 8 times its original length.

Example V A tow of polyacrylonitrile obtained by wet spinning It is pre-drawn by 10% of its initial length, whereafter it is immersed for minutes at room temperature in a methylethylketone bath containing 1% of butyl stearate calculated on the weight of the tow treated. It is thereafter readily drawn by a factor of 10, while a similar tow, treated only with water, can be drawn only with difficulty by more than 7 times its original length.

Example VI A polyacrylonitrile yarn obtained by dry spinning is treated with acetone just before it leaves the spinning cell. t is collected in a perforated pot, which is thereafter successively immersed in three acetone baths for 10 minutes in each bath, the last bath containing 0.8% of a condensation product of ethylene oxide with a fatty alcohol, calculated on the weight of the treated yarn. The yarn is thereafter readily drawn at elevated tem* perature to 11 times its initial length, while an identical yarn, which has undergone treatments with water instead of acetone, can only with difiiculty be drawn to more than 7 times its original length. Even in the cold state before the drawing, the yarn treated with acetone possesses a drawing capacity higher than 3, while that of a comparison yarn treated with water is only 1.5 under the same conditions.

Example VII A polyacrylonitrile yarn obtained by dry spinning is first washed in counter-current with water in order to remove the residual solvent. It is collected in a perforated pot, which is thereafter successively immersed in two baths containing of acetone and 30% of water for 10 minutes in each bath. The yarn thus treated can be readily drawn at elevated temperature to 11.5 times its original length, while a comparison yarn only washed with water and not treated with the acetone-water bath can only with difilculty be drawn to more than 6.8 times its original length.

I claim:

1. A process for improving the drawing properties of preformed filaments of a polymer selected from the class consisting of acrylonitrile homopolymers, copolymers and grafted polymers containing from to of acrylonitrile and up to 15 of at least one copolym erisable ethylenic compound, and mixtures of such polymers, prior to the final drawing of the said filaments, which comprises bringing the filaments completely into contact with an aliphatic ketone at least once between their exit from the spinning zone and their final drawing.

2. Process according to claim 1, wherein the spinning solvent is extracted from freshly spun acrylonitrile polymer filaments by means of the ketone.

3. Process according to claim 1 wherein the ketone employed is acetone.

4. Process according to claim 1 wherein the ketone.

employed is methyl ethyl ketone.

5. Process according to claim 1 wherein the ketone employed is diethyl ketone.

6. Process according to claim 1, wherein the ketone employed in at least the last of a plurality of treatments contains an oiling agent.

employed is acetone.

9. Process according to claim 7, wherein the ketone employed is methyl ethyl ketone.

10. Process according to claim 7, wherein the ketone employed is diethyl ketone.

References Cited in the file of this patent UNITED STATES PATENTS 2,579,451 Polson Dec. 18, 1951 2,589,294 Schmidt et a1. Mar. 18, 1952 2,768,868 Hewett et a1 Oct. 30, 1956 2,916,348

Cresswell Dec. 8, 1959 

1. A PROCESS FOR IMPROVING THE DRAWING PROPERTIES OF PREFORMED FILAMENTS OF A POLYMER SELECTED FROM THE CLASS CONSISTING OF ACRYLONTRILE HOMOPOLYMERS, COPOLYMERS AND GRAFTED POLYMERS CONTAINING FROM 85% TO 100% OF ACRYLONTIRILE AND UP TO 15% OF AT LEAST ONE COPOLYMERISABLE ETHYLENIC COMPOUND, AND MIXTURE OF SUCH POLYMERS, PRIOR TO THE FINAL DRAWING OF THE SAID FILAMENTS, WHICH COMPRISES BRINGING THE FILAMENTS COMPLETELY INTO CONTACT WITH AN ALIPHATIC KETONE AT LEAST ONCE BETWEEN THEIR EXIT FROM THE SPINNING ZONE AND THEIR FINAL DRAWING. 